In the phi phenomenon, for an eso deviation, the paddle motion direction when the eye is uncovered is which?

In the phi phenomenon, for an eso deviation, the paddle motion direction when the eye is uncovered is which?

• A. Opposite direction
• B. Same direction
• C. No movement
• D. Vertical movement

Answer: (A)

The phi phenomenon relies on how the brain combines rapidly alternating images from the two eyes to create a sense of motion. When there’s an eso deviation (an inward turning of one eye), the image seen by that eye sits displaced relative to the fellow eye’s image. Uncovering the eso-deviated eye sets up this offset, and the brain’s attempt to fuse the mismatched retinal inputs ends up reversing the perceived direction of the paddle’s motion. So the paddle appears to move in the opposite direction. The opposite-direction response reflects how misalignment and suppression influence motion perception in binocular vision.

The phi phenomenon relies on how the brain combines rapidly alternating images from the two eyes to create a sense of motion. When there’s an eso deviation (an inward turning of one eye), the image seen by that eye sits displaced relative to the fellow eye’s image. Uncovering the eso-deviated eye sets up this offset, and the brain’s attempt to fuse the mismatched retinal inputs ends up reversing the perceived direction of the paddle’s motion. So the paddle appears to move in the opposite direction. The opposite-direction response reflects how misalignment and suppression influence motion perception in binocular vision.